The nature of the bleaching stages of visual pigments will be investigated. Some model systems, a variety of polyenes which mimic the pigment chromophore, will be studied in order to learn about the state ordering and photochemistry of these systems. The primary emphasis of the project, however, will involve kinetic spectroscopic studies of rhodopsin to elucidate the nature of bleaching stages which are likely to have a direct physiological role in visual transduction. The bulk of the effort on the project will thus center on the kinetics of lumirhodopsin and metarhodopsin I bleaching stages.